Revert portions of 7acb141ed7f2dedd950bb65acf878098640d081e that attempt to use a function to hide jQuery metadata from JSON.stringify since this does not work reliably cross-browser (fails in Fx3.5, O11, Saf4).

Make sure that mousing over Chrome "internal div" doesn't trigger a mouseleave. Fixes #8209.
Follow up to https://github.com/jquery/jquery/commit/4a828c93d40eb67b2041b08bbed0f1973442bd03
which was stupid and got reversed.

Update $.data to use a function instead of an object when attaching to JS objects in order to hide attached metadata from JSON.stringify. Remove event.js code that was doing this before specifically for events, which is now redundant. Fixes #8108. 1.5-stable

Stores jQuery.ajaxSettings.isLocal locally at load time so that any change to it won't affect the transport. Fixes the url parsing regexp to deal with empty domains. Adds informative text into test/localfile.html and handles Opera's failure. Revises the way xhr are created by doing all tests at load time and normalizes all the xhr creation functions so that none of them may throw an exception.

Fixes #8152 by applying the same special cases for protocol "chrome-extension:" as were for "file:" (needs tests). Re-organizes and fixes the handling of special cases for HTTP status code in the xhr transport. Also re-organizes the handling of document.location in ajax.js.

Fixes #8135. Makes sure any exception thrown by Firefox when trying to access an XMLHttpRequest property when a network error occured is caught and notified as an error. Added test/networkerror.html to test the behavior.